Support Node Reference from references module

The export seems to work for me with this patch. Have not tested the import yet but will do it soon.

uuid_node_find() does not exist in latest uuid.
Attached patch is tested to export and import node_references.

However, if the imported node does not exist before the import and it has a node reference to itself, the feature will be overriden and the node misses the self-node-reference. Reverting the feature fixes this.

One file was left out from the prvious patch.

Note that References is deprecated in favor of Entity Reference. So you're recommended to use Entity Reference instead of References (or its sub-modules).

Re #5: I prefer using Entity Reference instead of References, too – but Entity References are NOT exported by their UUID, either. However, that's another issue: #1973770: Integration with users, entityreference, taxonomy term references, field collections and nodequeue items, but I couldn't check that one yet.

Attached is a reroll of #4 against 7.x-1.0-alpha3.

Unfortunately, at this time there's no plan to support the References module. Entity Reference is a well-maintained module which, I believe, is able to meet most people's needs in content referencing. Feel free to reopen the issue if you feel References has notable advantages over Entity Reference.

I don't know about any advantages of References over Entity Reference. For new sites I always use the latter. However, for old sites using former module this feature could be still very helpful.

Now as #1973770: Integration with users, entityreference, taxonomy term references, field collections and nodequeue items is in this needs definitely a re-roll and could profit from the newly introduced entity hooks. See the new uuid_features.api.php file.